Automatic telephone system.



A. E. LUNDELL.

AUTOMATIC TELEPHONE SYSTEM. APPLICATION FILED 0014,1915.

Patented July 17, 1917.

2 SHEETS-SHEET 1' m venior:

v A. E. LUNDELL. AUTOMATIC TELEPHONE SYSTEM. I APPLICATION FILED OCT- 4. 1915.

' Patented J uly 17, 1917.

2 SHEETS-SHEET 2- the rare tron.

ALBEN E. LUNDELL, OF NEW YORK, N. Y., ASSTGNOR, BY MESNE ASSIGNMENTS, TO

WESTERN ELECTRIC COMPANY, INCORPORATED, A CORPORATION OF NEW .YORK.

AUTOMATIC TELEPHONE SYSTEM.

To all whom it may concern:

Be it known that I, ALBEN E. LUNDELL, a citizen of the United States, residingat New York, in the county of Bronx and State of New York, have invented certain new and useful Improvements in Automatic Telephone Systems, of which the following is'a full, clear, concise, and exact description. i i

This invention relates to telephone eX- change systems employing trunk-hunting switches of the step-by-step type, and particularly to such systems wherein. the switches are driven over the trunk terminals from a common interrupter. It has been found in practice that where a number of trunk-hunting switches are stepped over multiple trunk terminals by impulses from a common interrupter that a number of such switches may, test multiples of the same trunk at the same time, since they are stepping over such multiples in synchronism. This may result in the same trunk being seized by a number of switches.

It is the object of this invention to provide a circuit arrangement wherein this difficulty is avoided, and wherein such interrupter operates only when necessary, that is to say, when a trunk-hunting switch is in the trunkhunting position.

In accordance with this invention, the,

trunks are multipled in groups to groups of selectors, and the interrupter for stepping the selectors comprlses a serles or string of relays. Each relay has a contact adapted to be included in circuit with the stepping magnets of one of the selectors of each of Y the aforesaid groups of selectors, no two of which selectors have access to the same trunk group. When any selector goes into mined relay of the string is reached, which unlocks the string and causes them to begin locking up again. This operation continues as long as the starting relay remains energized, which will be as long as there are selectors in the trunk-hunting position, the

starting relay becoming deenergized andstopping the operation of the interrupter when all the switches have found idle trunks. I

Referring to the drawing, Figure 1 is a diagram of the interrupter of this invention,

Specification of Letters Patent. Patmgtgd July 17, 1191?,

Application filed October 4, 1915. Serial No. 58,979. i

this view also showing three of the trunk- 21, 22, 23. Each of these sets is adapted to wipe over the trunk terminals 24, 25 and 26 of a different trunk group; that is to say, these trunk groups would not be multiples of each other. Similarly, c designates a conductor common to, say, ten trunk-hunt ing switches, each of which would have access to different groups of trunks. The group of trunk terminals t however, of one of the selectors associated with conductor 0 would be multiples of the terminals 24, 25,

26 of one of the selectors associated with conductor 0 as shown. Relay' 29 is the,

starting relay which is common to all the trunk-hunting switches. The invention will be more readily understood from a detailed description of the operation of the system.

Referring to Fig. 2, the calling line, whose substation is designated A, may be associated with the selector shown by a line finder or equivalent means, well known in the art. When the line has been thus extended, the following circuit is closed to energize stepping relay 10 at the selector: free pole of battery, right winding of relay 10, side-switch arm 1, conductor 11, line conductor 12, sender S, through the telephonic apparatus at substation A, line conductor 13, conductor 14, side-switch arm 2, left winding of relay 10, to ground. Relay 10 by attracting its armature energizes a slow relay 15. Relay 15 by attracting its armature interposes a break in the circuit of release magnet 16 of the selector and prepares a circuit for a slow relay 17 The subscriber at substation A now operates his sender S to transmit impulses corresponding to'thedigit of the wanted line with which this selector is concerned. Each time the sender'interrupts the line circuit, an impulse is delivered to the primary stepping magnet 18 over the following circuit: free. pole of battery, magnet 18, contact spring 30 top, armature and front contact of relay 15, armature and back contact of relay relay c, etc. "The retraction of the left ar- 10, to ground. Magnet 18 drives the brushes 2. 2.2, .23 n a p i ry. dir cti to .P'Q the same in operatiye r lation to the desired group of trunks. Upon the first retraction of the armature of the stepping relay 10, an impulse is sent to a slow relay 17, which, by e t re ns it armature, ene es a m gn t '19 by way of side-switch arm 4. This magnet 19 is the side-switch escapement magnet, andis constructed and arranged to re- '-lea'se the side switch from position 1 to position 2 upon its deenergization. Relay 17 ary stepping magnet 20 in circuit with the interrupter shown in Fig. f1. Referring now to Fig. 1, this circuit may be traced as fol- 'lows:-free pole of' ibattery, magnet 20, slde switch 5 and-its secondfcontaot, con- ;d u'ctor 9 might armature and back contact of relay qaconcluctor'81, relay-29 to ground. BelayQQ attracts its arniature,' locking itself n-p in series with relay in of the string over the following circuit: free pole of battery,

conductor 32, left armature and back contact of relay 7, arm 35 of switch 4; and its first contact, {armature .and trout contact of relay 2-9, relays a and 29-to ground. :Relay a, by attracting its right armature opens -the circuit of stepping magnet 20, and by attraet ing it s left armature closes the folflowing circuit to energize relay b free pole of battery, left armature and front contact of -relay "a, conductor 35, relay b to ground. Relay 1) at its left armature and front contact closes a circuit to energize relay 0,

whichiin turn, by attracting its left arma- ;ture, closes a c rcu t to ener'glze relay cl, etc. "llhelenergization ofrelay fopensthe circuit of relays a and 29. Relay )1, in retracting its right armature, closes the circuit ineluding stepping magnet 20 and relay 29. lS Ia'gnet 20' gives thefselector shaft another step,and relay a, in retracting Fits-left armature, unlocks-relay b, which in turn unlocks mature of relay f again locks up relays a and Relay a," by attractingjits right armature, opens the circuit of stepping magnet :20, and energizes relay 1 Relays 0, cl, e

" and then energize in succession as before.

Referring nowto Fig. 2, while the interrupter "1s operatingf as described, arm 4 connects the escapement magnet '19, in position'2,t0 the test brush -23. "Idle trun'ks are those upon whose test terminals 26 ground is present. Consequently, when the brush 2 eng e a g unded t s termina escapement magnet 19 becomes energized. The sidesiuitch is constructed to release its arms from position 2 to position 3 upon the enengization of escapement magnet 19. When the side switch goes into the third position, arm 5 in moving off its second contact opens the circuit of stepping magnet 20, thus stopping the switch. Side switch arm 5 also opens the circuit of relay 29, thus orminat'ing the operation of the interrupter, unless one or more .of the stepping magnets of the selectors which may be associated with the conductors c 0 etc are at this time operating. It is true that there may be a number of selectors testing in the same group at the same time; For example, brushes "21 22,28 may be testing the group to which terminals 24, 25, 26 belong, while l-bm shes b are testing multiplesr of such group. However, due to the circuit arrangement described, the impulses conveyed to the stepping magnets 2Q, 36 of such switches will begin at different times since the contacts of relays a, b are closed in rotation, and consequently the testing brushes will arrive .on multiples of the same {trunk different times; When the side switch anon-es :into position '3, arms 1 and- 2 connect conductors 11 and 14 through to the brushes 21 and 2 2, ithus cutting ofl' the relay 11-0. 'fllhe side switch in moving into position 8 closes circuit to operate 'a relay at the succeeding selector, which in attracting its-armature rcmoves ground from test w i-re 27,1thus rcndering thcseized trunk busy to othertcsting selectors.

The release of the selector may beeit'ectcd in any well-known manner, as the called party may, in restoring his receiver, cause a ground to be placed on-test conductor 27, which closes a circuit over test brush 23, side-switch arm 3 and off-normal contact 39 to the release magnet 16 of the selector, which in energizing, withdraws the .paiuls from the rratchets o'f thesclector shatt, thus restoring the same. The.releasemagnctalso restores the side switch in the well-known manner.

The switch 34 (Fig. 11) is "for the purpose of regulating the speed of the interrupter; that is tosay, the ,rate of impulses the interru-pter delivers to the stepping magnets. Arm 333 of such switch is'shown in contact with the first termina connected to the back contact otthesixthirelay i-n-the series. @011- sequently, :it ;is this relay which initiates the unloclring andlocking operations. When it desired to vary the rat e of impulses delivered. the arm 33 is moved into engagement with the contact corresponding .to the rate desired. It will 'be apparent thatias the arm is moved froinright to' left the rate is decreased. The switch 38 is provided to open the stepping circuit of magnet 20 in case the selector fails to find an idle trunk, this switch being opened in an extreme position of the selector brush shaft.

What is claimed is:

1. In a telephone exchange system, the combination with groups of automatic selector switches, groups of trunks multipled to said groups of switches and stepping magnets for driving said selectors over said trunks, of an interrupter for said magnets comprising a series of relays, each having a contact included in circuit with the magnets of a number of selectors, each selector having access to a different group of trunks, means for opening and closing said contacts in rotation, and means for arresting a selector on an idle trunk.

2. In a telephone exchange system, the combination with groups of automatic selector switches, groups of trunks multipled to said groups of switches and stepping magnets for driving said selectors over said trunks, of an interrupter for said magnets comprising a series of relays, each having a contact included in circuit with the magnets oi. a number of selectors equal to the number of relays in the series, each selector having access to a different group of trunks, means for opening and closing said contacts in rotation, and means for arresting a selector on an idle trunk.

3. In a telephone exchange system, the combination with groups of automatic selector switches, groups of trunks multipled to said groups of switches and stepping magnets for said selectors, of an interrupter for said magnets comprising a series of relays, each having a contact included in circuit with the magnets of a number of selectors whose trunk terminals are non-multiples of each other, a common relay adapted tobe included in circuit with any of said magnets and being adapted when energized to cause said relays to lock up in succession, the energization of a predetermined relay of the series unlocking said relays to again start a cycle of operations, and means for deenergizing said common relay to terminate the operation of said relays.

4. In a telephone exchange system, the combination with groups of automatic selector switches, groups of trunks multipled to said groups of switches and stepping magnets for said selectors, of an interrupter for said magnets comprising a series of relays, each having a contact included in circuit with the magnets of a number of selectors whose trunk terminals are non-multiples of each other, a common relay adapted to be included in circuit with any of said magnets and being adapted when energized to cause said relays to lock up in succession, the energization of a predetermined relay of the series unlocking said relays in succession, the unlocking of the last named relay again causing said relays'to lock up successively, and means for deenergizing said common relay to terminate the operation of said relays.

5. In a telephone exchange system, the combination with groups of automatic selector switches, groups of trunks multipled to said groups of switches, stepping magnets for said selectors, an interrupter for said magnets comprising a series of relays, each having a contact included in circuit with the magnets of a number of selectors whose terminals are non-multiples of each other, a common relay adapted to be included in circuit with any of said magnets and being adapted when energized to cause said relays to lock up in succession, the energization of a predetermined relay of the series unlocking said relays in succession, the unlocking of the last named relay again causing said relays to lock up successively, and means for varying the rate of impulses delivered to the magnets comprising a switch, the position of which determines the relay of the series which initiates the unlocking and locking operations.

In witness whereof, I hereunto subscribe my name this 29th day of September A. D., 1915.

ALBEN E. LUNDELL.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents. Washington, D. C. 

